Delimiting The Urban Development Boundry Based On Ecological Security

Under the background of rapid urbanization,problems such as the deterioration of the ecological environment and the imbalance between the supply and demand of land resources in the city and its surroundings have intensified the contradiction between urban man-land relations.At present,the country is vigorously promoting the construction of ecological civilization and comprehensively starting the preparation of national land spatial planning,and the delineation of urban development boundaries is one of the important contents of national land spatial planning.Although some experience has been accumulated in the delineation of the current urban development boundary,it is mainly concentrated in a few provincial capital cities,such as beijing and wuhan,and the practice in small and medium-sized cities in the plain area is still less.Plain terrain has simple terrain and few natural barriers that limit the expansion of urban construction land.Defining urban development boundaries of this type of area requires new theories and methods.Therefore,it is very strong to study how to delineate urban development boundaries in the absence of natural barrier restrictions Theoretical and practical significance.On the basis of reviewing domestic and foreign literature on urban ecological security and urban development boundaries,urban ecological security is regarded as the key goal of current urban planning and development,and urban planning needs to be based on the ecological background of the city to ensure sustainable construction.The urban development boundary includes a rigid development boundary and an elastic development boundary.The former is the bottom line of urban construction activities,and the latter is the construction space during the urban development period,which changes dynamically with time and social development.Taking the typical plain city Kaifeng downtown area as a research case,through the analysis of the spatial and temporal characteristics evolution of land use types and construction land in Kaifeng downtown area,it was found that the land use changes and construction land expansion in the past five years were mainly concentrated in the west of Longting District,the main reason is concentrated in the social economy,including population growth,economic development and other external factors.Based on the urban ecological background,select the ecological protection red line,urban water system,forest land resources,cultivated land and urban special land composed of military land,railways,highways,historical and cultural resources in the city as rigid development boundary demarcation index factors,Scientifically define the scope of rigid management and control buffer areas of various indicators.With the help of factor superposition analysis,it is found that the area of rigid ecological protection space where the city cannot carry out construction activities is 13145.42hm2,accounting for 23.28% of the total area of the main urban area,mainly concentrated in the north and Southeast of Yuwangtai District.Under the need of ensuring urban social and economic development,six urban construction land expansion sensitive factors,such as the park green space,the urban built-up area,the public service facilities,the commercial center,the industrial agglomeration area and the highway,are selected for evaluation and analysis of land suitability.Based on the grey prediction value of the number of permanent residents and the scale of construction land in the central city in 2025,the suitability evaluation grade results are screened according to the principle of high to low to expand the scope and direction of urban construction land expansion,and the preliminary urban flexible development boundary is obtained,the area of space available for construction activities is 24181.56hm2,accounting for 43.80% of the total area of the main city.After determining the rigid urban development boundary and the preliminary elastic development boundary,the two will be superimposed and the rigid elements in the preliminary elastic space will be removed by the principle of elastic concession rigidity,so as to delimit the urban development boundary of Kaifeng downtown area.The annual space management area of the city where construction activities can be concentrated is 20659.7hm2,accounting for 36.59% of the total area of the main city.Based on the delineation of the boundary,according to the characteristics of the control elements,based on the strength and intensity of the control,classification management and control measures are proposed.